A moisture and heat exchanging unit is employed for maintaining moisture and temperature of air, inhaled through a respiration device such as a tracheal tube or tracheotomy canula opening to ambient air or connected to a respirator, close to levels prevailing under normal breathing through the upper airways. Such unit also reduces the humidity of exhaled air, thus reducing condensation of water in tubes, respirator equipment etc. Moisture and heat exchanging units comprising a housing holding therein a porous structure impregnated with a hygroscopic compound are known in the art.
The traditional way of connecting respirator tubing to a patient involves the use of a Y-piece, a heat and moisture exchanger, a bacterial filter, a swivel and a flexible tube arrangement for stress-free connection to the patient tracheal tube, and also a T-piece adapter for connecting a gas analyzer sampling line.
The use of many different connecting components between the ventilator tubing and the patient in this way results in a bulky and space-demanding arrangement with a large dead space and many different connecting surfaces that are all potential air leaks. Normally, low cost swivel arrangements that do not include the use of separate sealing elements like O-rings are also associated with a certain "tolerable" leakage.
Although certain combination units are now available, e.g. filter-humidifier, humidifier with sampling port etc., in order to reduce the total number of connecting components, the use of several components tends to be expensive.
The abstract and drawings of SE-B-467685 discloses a device for moisturizing, heating and filtering of breathing air having one first opening connectible to a tracheal tube and at least one opening for inlet and outlet of air. A heat exchanging body is arranged within the device in such manner that the inhaled and exhaled air will pass therethrough via first and second surfaces, at least one of which being covered with a waved or folded filter for retaining bacteria and/or virus. In the embodiment shown, the apparatus has an oval cross-section with the inlet and outlet openings extending axially.
The abstract and drawings of SE-B-462367 discloses a breathing valve comprising a valve house holding a membrane and a filter. The house has an axial sleeve at one end. A heat exchanging shield with an inhalation channel in arranged at the opposite end of the housing, extending radially to enable pre-heating of the inhaled air by the patient's body heat.
Prior art devices are space-demanding, rigid and expensive. A more slim arrangement is desirable, provided that it can be made at low expense, with a minimum number of parts and with good sealing between the parts. A further demand is an adaptable design where inlet and outlet openings can be directed at different angles in relation to each other. However, devising an adaptable design is liable to encountering problems with loss of sealing capacity in the junction between the parts of the device. Many known sealing means such as O-rings or close fitting structures with exact dimensions are too expensive to be used in a disposable product.